Pumping chamber for a liquefracture handpiece

ABSTRACT

A surgical handpiece having at least two lumens or tubes mounted to a body. At least one tube is used for aspiration and at least one other tube is used to inject heated surgical fluid for liquefying a cataractous lens. A portion of the second tube is enlarged to form a pumping chamber. The pumping chamber works by boiling a small volume of the surgical fluid. As the fluid boils, it expands rapidly, thereby propelling the liquid downstream of the pumping chamber out of the second tube. The pumping chamber may use a pair of electrodes.

[0001] This application is a continuation-in-part application of U.S.patent application Ser. No. 09/090,433, filed Jun. 4, 1998.

BACKGROUND OF THE INVENTION

[0002] This invention relates generally to the field of cataract surgeryand more particularly to a pumping chamber for a handpiece forpracticing the liquefracture technique of cataract removal.

[0003] The human eye in its simplest terms functions to provide visionby transmitting light through a clear outer portion called the cornea,and focusing the image by way of the lens onto the retina. The qualityof the focused image depends on many factors including the size andshape of the eye, and the transparency of the cornea and lens.

[0004] When age or disease causes the lens to become less transparent,vision deteriorates because of the diminished light which can betransmitted to the retina. This deficiency in the lens of the eye ismedically known as a cataract. An accepted treatment for this conditionis surgical removal of the lens and replacement of the lens function byan artificial intraocular lens (IOL).

[0005] In the United States, the majority of cataractous lenses areremoved by a surgical technique called phacoemulsification. During thisprocedure, a thin phacoemulsification cutting tip is inserted into thediseased lens and vibrated ultrasonically. The vibrating cutting tipliquifies or emulsifies the lens so that the lens may be aspirated outof the eye. The diseased lens, once removed, is replaced by anartificial lens.

[0006] A typical ultrasonic surgical device suitable for ophthalmicprocedures consists of an ultrasonically driven handpiece, an attachedcutting tip, and irrigating sleeve and an electronic control console.The handpiece assembly is attached to the control console by an electriccable and flexible tubings. Through the electric cable, the consolevaries the power level transmitted by the handpiece to the attachedcutting tip and the flexible tubings supply irrigation fluid to and drawaspiration fluid from the eye through the handpiece assembly.

[0007] The operative part of the handpiece is a centrally located,hollow resonating bar or horn directly attached to a set ofpiezoelectric crystals. The crystals supply the required ultrasonicvibration needed to drive both the horn and the attached cutting tipduring phacoemulsification and are controlled by the console. Thecrystal/horn assembly is suspended within the hollow body or shell ofthe handpiece by flexible mountings. The handpiece body terminates in areduced diameter portion or nosecone at the body's distal end. Thenosecone is externally threaded to accept the irrigation sleeve.Likewise, the horn bore is internally threaded at its distal end toreceive the external threads of the cutting tip. The irrigation sleevealso has an internally threaded bore that is screwed onto the externalthreads of the nosecone. The cutting tip is adjusted so that the tipprojects only a predetermined amount past the open end of the irrigatingsleeve. Ultrasonic handpieces and cutting tips are more fully describedin U.S. Pat. Nos. 3,589,363; 4,223,676; 4,246,902; 4,493,694; 4,515,583;4,589,415; 4,609,368; 4,869,715; 4,922,902; 4,989,583; 5,154,694 and5,359,996, the entire contents of which are incorporated herein byreference.

[0008] In use, the ends of the cutting tip and irrigating sleeve areinserted into a small incision of predetermined width in the cornea,sclera, or other location. The cutting tip is ultrasonically vibratedalong its longitudinal axis within the irrigating sleeve by thecrystal-driven ultrasonic horn, thereby emulsifying the selected tissuein situ. The hollow bore of the cutting tip communicates with the borein the horn that in turn communicates with the aspiration line from thehandpiece to the console. A reduced pressure or vacuum source in theconsole draws or aspirates the emulsified tissue from the eye throughthe open end of the cutting tip, the cutting tip and horn bores and theaspiration line and into a collection device. The aspiration ofemulsified tissue is aided by a saline flushing solution or irrigantthat is injected into the surgical site through the small annular gapbetween the inside surface of the irrigating sleeve and the cutting tip.

[0009] Recently, a new cataract removal technique has been developedthat involves the injection of hot (approximately 45° C. to 105° C.)water or saline to liquefy or gellate the hard lens nucleus, therebymaking it possible to aspirate the liquefied lens from the eye.Aspiration is conducted with the injection of the heated solution andthe injection of a relatively cool solution, thereby quickly cooling andremoving the heated solution. This technique is more fully described inU.S. Pat. No. 5,616,120 (Andrew, et al.), the entire contents of whichis incorporated herein by reference. The apparatus disclosed in thepublication, however, heats the solution separately from the surgicalhandpiece. Temperature control of the heated solution can be difficultbecause the fluid tubings feeding the handpiece typically are up to twometers long, and the heated solution can cool considerably as it travelsdown the length of the tubing.

[0010] Therefore, a need continues to exist for a control system for asurgical handpiece that can heat internally the solution used to performthe liquefracture technique.

BRIEF SUMMARY OF THE INVENTION

[0011] The present invention improves upon the prior art by providing asurgical handpiece having at least two lumens or tubes mounted to abody. At least one tube is used for aspiration and at least one othertube is used to inject heated surgical fluid for liquefying acataractous lens. A portion of the second tube is enlarged to form apumping chamber. The pumping chamber works by boiling a small volume ofthe surgical fluid. As the fluid boils, it expands rapidly, therebypropelling the liquid downstream of the pumping chamber out of thesecond tube. The pumping chamber may use a pair of electrodes, at leastone of the electrodes containing a countersink.

[0012] Accordingly, one objective of the present invention is to providea surgical handpiece having at least two tubes.

[0013] Another objective of the present invention is to provide asurgical handpiece having a pumping chamber with two electrodes, atleast one electrode containing a countersink.

[0014] Another objective of the present invention is to provide asurgical handpiece having a device for delivering the surgical fluidthrough the handpiece in pulses.

[0015] These and other advantages and objectives of the presentinvention will become apparent from the detailed description and claimsthat follow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a front, upper left perspective view of the handpiece ofthe present invention.

[0017]FIG. 2 is a rear, upper right perspective view of the handpiece ofthe present invention.

[0018]FIG. 3 is a cross-sectional view of the handpiece of the presentinvention taken along a plane passing through the irrigation channel.

[0019]FIG. 4 is a cross-sectional view of the handpiece of the presentinvention taken along a plane passing through the aspiration channel.

[0020]FIG. 5 is an enlarged partial cross-sectional view of thehandpiece of the present invention taken at circle 5 in FIG. 4.

[0021]FIG. 6 is an enlarged partial cross-sectional view of thehandpiece of the present invention taken at circle 6 in FIG. 3.

[0022]FIG. 7 is an enlarged cross-sectional view of the handpiece of thepresent invention taken at circle 7 in FIGS. 3 and 4, and showing aresistive boiler pump.

[0023]FIG. 8 is an exploded, partial cross-section view of oneembodiment of the handpiece of the present invention.

[0024]FIG. 9 is a block diagram of a control system that can be usedwith the handpiece of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0025] Handpiece 10 of the present invention generally includeshandpiece body 12 and operative tip 16. Body 12 generally includesexternal irrigation tube 18 and aspiration fitting 20. Body 12 issimilar in construction to well-known in the art phacoemulsificationhandpieces and may be made from plastic, titanium or stainless steel. Asbest seen in FIG. 6, operative tip 16 includes tip/cap sleeve 26, needle28 and tube 30. Sleeve 26 may be any suitable commercially availablephacoemulsification tip/cap sleeve or sleeve 26 may be incorporated intoother tubes as a multi-lumen tube. Needle 28 may be any commerciallyavailable hollow phacoemulsification cutting tip, such as theTURBOSONICS tip available from Alcon Laboratories, Inc., Fort Worth,Tex. Tube 30 may be any suitably sized tube to fit within needle 28, forexample 29 gauge hypodermic needle tubing.

[0026] As best seen in FIG. 5, tube 30 is free on the distal end andconnected to pumping chamber 42 on the proximal end. Tube 30 and pumpingchamber 42 may be sealed fluid tight by any suitable means having arelatively high melting point, such as a silicone gasket, glass frit orsilver solder. Fitting 44 holds tube 30 within bore 48 of aspirationhorn 46. Bore 48 communicates with fitting 20, which is journaled intohorn 46 and sealed with O-ring seal 50 to form an aspiration pathwaythrough horn 46 and out fitting 20. Horn 46 is held within body 12 byO-ring seal 56 to form irrigation tube 52 which communicates withirrigation tube 18 at port 54.

[0027] As best seen in FIG. 7, in a first embodiment of the presentinvention, pumping chamber 42 contains a relatively large pumpingreservoir 43 that is sealed on both ends by electrodes 45 and 47.Electrical power is supplied to electrodes 45 and 47 by insulated wires,not shown. In use, surgical fluid (e.g. saline irrigating solution)enters reservoir 43 through port 55, tube 34 and check valve 53, checkvalves 53 being well-known in the art. Electrical current (preferablyRadio Frequency Alternating Current or RFAC) is delivered to and acrosselectrodes 45 and 47 because of the conductive nature of the surgicalfluid. As the current flows through the surgical fluid, the surgicalfluid boils. As the surgical fluid boils, it expands rapidly out ofpumping chamber 42 through port 57 and into tube 30 (check valve 53prevents the expanding fluid from entering tube 34). The expanding gasbubble pushes the surgical fluid in tube 30 downstream of pumpingchamber 42 forward. Subsequent pulses of electrical current formsequential gas bubbles that move surgical fluid down tube 30. The sizeand pressure of the fluid pulse obtained by pumping chamber 42 can bevaried by varying the length, timing and/or power of the electricalpulse sent to electrodes 45 and 47 and by varying the dimensions ofreservoir 43. In addition, the surgical fluid may be preheated prior toentering pumping chamber 42. Preheating the surgical fluid will decreasethe power required by pumping chamber 42 and/or increase the speed atwhich pressure pulses can be generated.

[0028] Preferably, electrode 45 contains small depression or countersink100 having any suitable depth but approximately 0.003 inches beingpreferred. Pumping reservoir 43 is narrowest at periphery 101 (on theorder of 0.1 mm) and as a result, fluid in pumping reservoir 43 boilsfirst at periphery 101 and the steam wave front travels down countersink100 toward the central axis of tube 30. The surgical fluid conductselectricity much better in the liquid state than in the vapor state.Consequently, current flow diminishes greatly at periphery 101 whereboiling occurs first.

[0029] While several embodiments of the handpiece of the presentinvention are disclosed, any handpiece producing adequate pressure pulseforce, rise time and frequency may also be used. For example, anysuitable handpiece producing a pressure pulse force of between 0.03grams and 50.0 grams (between 1 gram and 50.0 grams being preferred),with a rise time of between 1 gram/second and 50,000 grams/second (withbetween 500 grams/second and 50,000 grams/second being preferred) and afrequency of between 1 Hz and 200 Hz may be used, with between 10 Hz and100 Hz being most preferred. The pressure pulse force and frequency maybe varied with the hardness of the material being removed. For example,the inventors have found that a lower frequency with a higher pulseforce is more efficient at debulking and removing the relatively hardnuclear material, with a higher frequency and lower pulse force beinguseful in removing softer epinuclear and cortical material. Infusionpressure, aspiration flow rate and vacuum limit are similar to currentphacoemulsification techniques.

[0030] As seen in FIG. 9, one embodiment of control system 300 for usein operating handpiece 310 includes control module 347, RF amplifier 312and function generator 314. Power is supplied to RF amplifier 312 by DCpower supply 316, which preferably is an isolated DC power supplyoperating at ±200 volts. Control module 347 may be any suitablemicroprocessor, and may receive input from operator input device 318.Function generator 314 provides the electric wave form to amplifier 312and preferably operates at 450 KHz to help minimize corrosion.

[0031] In use, control module 347 receives input from surgical console320. Console 320 may be any commercially available surgical controlconsole such as the LEGACY® SERIES TWENTY THOUSAND® surgical systemavailable from Alcon Laboratories, Inc., Fort Worth, Tex. Console 320 isconnected to handpiece 310 through irrigation line 322 and aspirationline 324, and the flow through lines 322 and 324 is controlled by theuser via footswitch 326. Irrigation and aspiration flow rate informationin handpiece 310 is provided to control module 347 by console 320 viainterface 328, which may be connected to the ultrasound handpiececontrol port on console 320 or to any other output port. Control module347 uses footswitch 326 information provided by console 320 and operatorinput from input device 318 to generate two control signals 330 and 332.Signal 332 is used to operate pinch valve 334, which controls thesurgical fluid flowing from fluid source 336 to handpiece 310. Fluidfrom fluid source 336 is heated in the manner described herein. Signal330 is used to control function generator 314. Based on signal 330,function generator 314 provides a wave form at the operator selectedfrequency and amplitude determined by the position of footswitch 326 toRF amplifier 312 which is amplified to advance the powered wave form tohandpiece 310 to create heated, pressurized pulses of surgical fluid.

[0032] As best seen in FIGS. 3, 4 and 7, surgical fluid may be suppliedto pumping chamber 43 through tube 34 or, as seen in FIG. 8, surgicalfluid may be supplied to pumping chamber 243 through irrigation fluidtube 234 which branches off main irrigation tube 235 supplying coolsurgical fluid to the operative site. As seen in FIG. 8, aspiration tube237 may be contained internally to handpiece 10.

[0033] Any of a number of methods can be employed to order limit theamount of heat introduced into the eye. For example, the pulse trainduty cycle of the heated solution can be varied so that the total amountof heated solution introduced into the eye does not vary with the pulsefrequency. Alternatively, the aspiration flow rate can be varied as afunction of pulse frequency so that as pulse frequency increasesaspiration flow rate increases proportionally.

[0034] This description is given for purposes of illustration andexplanation. It will be apparent to those skilled in the relevant artthat changes and modifications may be made to the invention describedabove without departing from its scope or spirit. For example, it willbe recognized by those skilled in the art that the present invention maybe combined with ultrasonic and/or rotating cutting tips to enhanceperformance.

We claim:
 1. A liquefracture handpiece, comprising: a) a body having afirst irrigation lumen; and b) a pumping chamber attached to the firstirrigation lumen, the pumping chamber capable of producing pressurepulses with i) a force of between 0.03 grams and 50.0 grams, ii) a risetime of between 1 gram/second and 50,000 grams/second and iii) afrequency of between 1 Hz and 200 Hz.
 2. The handpiece of claim 1wherein the force of the pressure pulse is between 1.0 gram and 50.0grams.
 3. The handpiece of claim 1 wherein the rise time of the pressurepulse is between 500 grams/second and 50,000 grams/second.
 4. Aliquefracture handpiece, comprising: a) a body having a first irrigationlumen; and b) a pumping chamber attached to the first irrigation lumen,the pumping chamber capable of producing pressure pulses with a force ofbetween 0.03 grams and 50.0 grams.
 5. The handpiece of claim 4 whereinthe force of the pressure pulse is between 1.0 gram and 50.0 grams.
 6. Aliquefracture handpiece, comprising: a) a body having a first irrigationlumen; and b) a pumping chamber attached to the first irrigation lumen,the pumping chamber capable of producing pressure pulses with a risetime of between 1 gram/second and 50,000 grams/second.
 7. The handpieceof claim 6 wherein the rise time of the pressure pulse is between 500grams/second and 50,000 grams/second.